Technical Field
Described herein is a device comprising members in a kinematic relationship, the kinematic relationship at least partially governed by at least one magnetic flux interaction that, in effect, may provide a tunable resistance to movement, changing the rate of relative movement between the members.
Description of the Related Art
Eddy current formation may be used in a variety of ways to adjust the rate of movement of a member. Various apparatus exist, for example in abseiling, to control the descent of a climber or for example, in personal protective equipment scenarios to prevent an injury causing fall. Other applications that use eddy current generation are in controlling pay-out of line in trains, cable cars, zip line devices and roller coasters.
One art device is published as US2012/0055740. This device utilizes a rotor assembly with arms that move relative to the rotor. The arms themselves may be conductive or magnetic or may have conductive or magnetic members attached thereto. When a rotational force is applied to the rotor, the arms move outwards from a central axis via centrifugal force and into a magnetic (or conductive) field. As the arms move through the field, eddy currents are generated, the strength of which is dependent on the speed of rotation. As the speed of rotation reduces, the arms are drawn back towards the axis of rotation via springs and/or a reduced centrifugal force acting on the arms. This device is widely used and provides an excellent means of changing the relative speed of parts.
One aspect of the above apparatus is that control on the speed of activation of the braking effect caused by movement of the arms into the magnetic field can only be tuned by adjusting a few variables including bias strength, arm weight (and hence inertia) and pivot axis placement—influenced by either the degree of offset from a center of mass of the arm and/or the degree of offset of the pivot axis from the rotor axis.
Tuning movement of the arms once movement commences via an additional input may also be useful depending on the end application of the device or at least it provides the public with a choice.
Further aspects and advantages of the device will become apparent from the ensuing description that is given by way of example only.